This invention relates to a multi-effect distillation process and apparatus for accomplishing the same.
More particularly, the invention relates to a thermally driven multi-effect distillation process and apparatus which can be employed in a wide variety of applications such as, for example, the desalting of sea water, toxic liquid waste concentration, alcohol production and the like.
A wide variety of single and multi-effect distillation processes and apparatus for achieving the same are known. For example, U.S. Pat. No. 2,180,052 discloses a vacuum distillation apparatus in which a centrifugal vaporizing surface and a stationary condensing surface are employed. U.S. Pat. No. 2,210,926 deals with a vacuum distillation process in which materials, such as fish oils, are heated and when in such physical state subjected to rapid vaporization. U.S. Pat. Nos. 2,210,927 and 2,210,928 deal with a vacuum distillation process and apparatus in which material to be distilled is subjected to heat and placed under a high vacuum in such a form or condition so that rapid vaporization takes place over a short path and by means of force greater than, or means other than gravity, thereby avoiding substantial decomposition of the distillate. The apparatus for accomplishing the process generally comprises separate rotating vaporizing and condensing surfaces. A somewhat similar apparatus and process is shown in U.S. Pat. No. 2,298,377 except that the vaporizing surface is heated to different temperatures at different areas thereof and the process deals with separately condensing vapor fractions from different areas of the vaporizing surface on an unheated condensing surface. A modified but somewhat similar device is shown in U.S. Pat. No. 2,308,008 except that a hot condensing surface, as well as a hot vaporizing surface, is employed.
In U.S. Pat. No. 2,551,815 a multi-effect centrifugation apparatus and process is disclosed in which material to be separated is passed through a series of centrifugation effects, the lighter fraction removed in each effect being passed continuously to a succeeding effect richer in a lighter component and the heavier fraction removed in each effect being passed continuously to a preceding effect richer in a heavier component. On the other hand, U.S. Pat. No. 2,734,023 deals with a compression distillation method and apparatus in which the resistance to the flow of heat through evaporating and/or condensing films and the resistance to separation of vapor from the distilland are greatly reduced. A somewhat similar device is disclosed in U.S. Pat. No. 2,894,879 for distilling liquid such as sea water by using rotary phase separator barriers of the type described in U.S. Pat. No. 2,734,023 but connected in series. Still another compression still is disclosed in U.S. Pat. No. 2,899,366 in which a combination of degassing and puring means for removal of interfering gases is employed.
U.S. Pat. No. 2,999,796 deals with a multiple and centrifugal separator employing stacked evaporating chambers mounted for rotation on a vertical axis and including an enclosing vacuum chamber disposed around the stacked evaporating chambers.
U.S. Pat. No. 3,136,707 discloses a phase separation barrier distillation apparatus in which means, such as spreaders or wipers are employed to spread and remove liquid from evaporating and condensing surfaces. U.S. Pat. No. 3,271,271 discloses a still which also employs spreading and wiping means. On the other hand, U.S. Pat. No. 3,788,954 discloses an interphase mass transfer process and apparatus in which the components of a fluid having different vapor pressure are transferred between their liquid and vapor phases and in which the liquid and vapor phases are in thermodynamic equilibrium.
British Pat. No. 549,519 discloses a high vacuum distillation apparatus which has highly polished vaporizing and condensing surfaces that are separated by a substantially unobstructed space and French Pat. No. 1,162,054 discloses a distillation process in which liquid to be distilled is passed into a zone where energy is added thereto and then discharged from that zone in the form of a thin film which is then contacted with a current of distilling vapor that is passed across the surface of the film.
While the various processes and apparatus briefly described above have been generally useful and acceptable in various areas of technology where liquid separation is employed, there still exists a need for even further types of such distillation processes and apparatus which, while exhibiting great efficiency, are relatively simple in operation and physical structure and, at the same time, advantageous in terms of manufacturing and operating costs. The present invention fulfills such a need.